But the Lord hath taken you, and brought you forth out of the iron furnace, even out of Egypt, to be unto him a people of inheritance, as ye are this day. (Deuteronomy 4:20)
In 1 Kings 8:51 and Jer. 11:4 this figure of speech is used to denote harsh servitude. Isaiah defines the disciplinary experiences under God’s hand as a process of refining in a furnace (Isa. 48:10; see also Job 23:10).